The paper presents an overview of various types of carbon matrices with a high specific surface area and the technology of filling them with chemically active and auxiliary materials. The main attention is paid to promising matrices based on metal-organic frameworks (MOFs) and on commercially available rolled carbon materials such as Busofit. Their structural features are considered and their classification is presented. The main methods and approaches to the synthesis of both MOFs themselves and composite materials based on them are considered.
As one of the options for changing the properties of MOFs and composite materials based on them, an approach based on doping MOFs with a ZIF-67 structure with another metal is presented. In particular, the scientific team of authors implemented the synthesis of cobalt MOFs, in which Co is partially replaced by manganese at the synthesis stage. In addition, a simple synthesis technique was used by coprecipitation in an aqueous solution, but modified by ultrasonic exposure, which reduces the duration of the synthesis. Electrochemical studies have shown that the specific electrochemical capacity of electrodes from pyrolyzed MOFs with partial substitution of cobalt with manganese is significantly higher than that of materials without manganese. With an increase in the manganese content in MOFs, both the specific capacity and the energy density increase. Doping MOFs with Mn allows for a significant (from 100 to 298 F/g at a current density of 0.25 A/g) improvement in the electrochemical characteristics of electrode materials for hybrid supercapacitors based on them. The results obtained by the authors indicate that substituting cobalt with manganese is an effective way to improve the electrochemical characteristics of MOFs.

Using the method of HF cathode sputtering in an oxygen atmosphere, Ba₂NdFeNb₄O₁₅/Si(001) heterostructures with layer thicknesses from 75 to 1000 nm were manufactured. Their crystal structure, surface morphology, dielectric characteristics and features of the formation of the ferroelectric state were investigated. It has been established that the films are polycrystalline textured with a predominant orientation of the axes [001] in the direction normal to the substrate surface, in which a significant deformation of the unit cell was observed. It was found that as the thickness of the films increases, the roughness of their surface increases and follows the scaling law. From the volt-farad characteristics (in terms of displacement and hysteresis width), it was found that with a decrease in thickness, the coercive field increases and the internal field increases. This was also confirmed by measuring local residual hysteresis loops using piezoelectric force microscopy. In addition, by the local application of positive and negative external fields, it is possible to form polarized regions in which, in one case, the polarization vector is directed from the substrate to the surface of the film, and in the other, on the contrary, from the film to the substrate. Also, the effective piezoelectric coefficient was determined for all the studied heterostructures. The reasons for the revealed patterns are discussed. 

A program has been developed for modeling the currents of a detector based on a p–i–n structure exposed to gamma radiation in the low-energy range from 1 to 30 keV. The program allows one to take into account the contribution of different regions of the structure (p⁺, n⁺, and the space charge region) to the detector current, which makes it possible to analyze changes in the spectral dependences of the detector current. The basic pixel size was 10×10 μm². Two types of structures were used for modeling: with an n⁺ region between two p⁺ regions on the structure surface and without this dividing region. In order to optimize the design and improve the efficiency of collecting X-ray quanta, the dependences of the spectral characteristics of the structure current on geometrical, technological parameters, and the applied voltage were considered. It was shown that the thickness of the lightly doped region and the reverse voltage applied to the structure have the greatest influence on the type of spectral characteristics of the current. Comparisons of detector characteristics for structures of two different designs are carried out.

The article discusses the technology of obtaining nanodisperse powders of cerium, yttrium and gadolinium oxides. The process is based on the precipitation of carbonates from (REM) nitrates and their thermal decomposition. It was found that the particle sizes of nanodispersed REM oxide powders depend on the concentration of the initial nitrate solution of the rare earth metal, the speed of the carbonate deposition process, as well as the parameters of its thermal decomposition – temperature and time. The rapid and uniform supply of the precipitator in this work was realized by injecting a solution of (NH₄)₂CO₃ into a constantly stirring reaction mass. The optimal heat treatment temperature was selected for each of the oxides. As a result of the work, kilogram batches of nanoscale powders of cerium, yttrium and gadolinium oxides with particle sizes in the range from 15 to 30 nm were obtained, the single-phase nature of which was confirmed by X-ray phase analysis data, and the particle sizes were determined using transmission electron microscopy.

The effect of deposited aggregates of Co–CoO nanoparticles with an average diameter of 160 nm on the charge carrier concentration and carrier transport mechanisms in Co–CoO/graphene/SiO₂ hybrid structures has been studied. The structures were obtained by electrochemical deposition of cobalt nanoparticles onto the surface of single-layer CVD graphene in a reverse galvanostatic mode from an electrolyte containing CoSO₄∙6H₂O (1.25 g/l) and NaCl (0.064 g/l) mixture at a cathodic current density of 2.5 mA/cm² and an anodic current density 1.25 mA/cm². It has been shown that deposition of Co–CoO nanoparticles results in an almost twofold decrease in conductivity of structure. We attribute this effect to the exclusion of some of the intrinsic defects of graphene from the carrier transport process in the structure under study.
The coexistence of mechanisms of quantum corrections (QC) to the Drude conductivity under conditions of weak localization and usual band (activational) conductivity was discovered. The dominance of the QC to conductivity both before and after the Co–CoO particles deposition, as well as a decrease in the value of the pre-exponential factor σ_a0, included in the activational mechanism, from 2.8∙10^-4 S to 3.1∙10^-5 S were observed after particle deposition.

The dielectric properties and switching processes of polarization in single crystals of strontium barium niobate S_r0.61Ba_0.39Nb₂O₆ (SBN61) doped with holmium (Ho³⁺) and thulium (Tm³⁺) ions were studied. Dielectric measurements showed that the incorporation of these ions in the crystal lattice led to an increase of the dielectric constant (ε) and an ambiguous change in dielectric loss tangent (tan δ). In addition, the effect of a constant electric field (polarizing effect) on the dielectric parameters of the crystals was studied. Dielectric permittivity of SBN61 crystals undoped and doped with Tm³⁺ (SBN61:Tm) was decreased after the dc-field, while a value of ε for SBN61 doped with Ho³⁺ (SBN61:Ho) and holmium + thulium ions (SBN61:Tm+Ho) was increased. For all samples, the dielectric loss tangent became lower due to polarizing process. Temperature behavior study of the dielectric constant revealed that the presence of thulium and holmium ions into SBN61 crystal lattice caused decreasing the maximum value of ε in the phase transition region and broadening the Curie region. For the SBN61:Ho and SBN61:Tm+Ho samples, the broadest diffusion of the dielectric constant maximum was observed near the phase transition region. On the base of ferroelectric hysteresis loops, the polarization switching processes were studied in the samples under an ac-field up to 4 kV/cm at room temperature. Main features of the switching processes of the SBN61 samples doped with Ho³⁺ and Tm³⁺ were noted. In crystals doped with holmium ions as well with a low thulium ions concentration, the coercive field value (EC) was significantly higher and the switched polarization (P) was lower as compared to pure SBN61 samples and crystals doped with a high holmium concentration. The study results obtained for SBN crystals doped with thulium and holmium ions were discussed on the base of structural disorder and domain structure changes depending on the type and concentration of the doping ions.

Photoluminescent properties of indium arsenide autoepitaxial layers have been investigated by low-temperature Fourier-transform infrared spectroscopy. The structures were grown by hydride vapour-phase epitaxy on heavily doped n⁺-InAs substrates. Sulfide passivation of the substrates was carried out in a unimolar aqueous solution of sodium sulfide at room temperature, which leads to the removal of the natural oxide layer and the formation of a sulfur layer protecting the substrate surface. Three distinct peaks were detected in the photoluminescence spectra of the structures measured on a Fourier-transform infrared spectrometer at 8 K. The peak with an energy of 415 meV corresponds to the direct interband transition in indium arsenide. The power dependence of the second peak, with an energy of 400 meV, has a sublinear character, which allowed us to attribute it to the emission of bound excitons. A structure with a series of closely spaced peaks was observed in the PL line of the third peak with a maximum at an energy of 388 meV, which allows us to attribute this signal to the emission of donor-acceptor pairs. The effect of substrate sulfidisation on the quality of InAs epitaxial layers was assessed by comparing the relative area of the PL peak of bound excitons for sulfidised and non-sulfidised structures. It is shown that the decrease in the relative peak area of bound excitons after substrate sulfidisation is due to a decrease in the number of defects in the InAs autoepitaxial layers. 

The production of ferroelectric membrane-type structures was carried out in several sequential operations. First, wells were etched on a silicon (100) n-type plate with a thickness of 250 µm with a natural oxide on the surfaces in a hydrofluoric acid solution of 70 wt.% HF+30 wt.% H₂O and a membrane blank was obtained. The diameter of the recesses in the silicon wafer at the base was 1.2 mm. Then, a 300 nm Ba_0.8Sr_0.2TiO₃ layer and contact electrodes were deposited on the flat surface of the membrane blank. The minimum thickness of the n-Si substrate was 20 µm. Comparative measurements of high-frequency C–V-characteristics of metal-ferroelectric-semiconductor objects grown on thin (20 µm) and thick (750 µm) substrates were carried out at room temperature. A change in capacitive properties of samples was found with a decrease in the thickness of the substrate on which they were formed. In objects grown on a thin substrate, compared with those formed on a thick one, branches of the C–V-characteristic are shifted towards negative voltages by 4 V and the width of the hysteresis loop is 3÷4 V larger.  A decrease in the "tightness" of the ferroelectric film with a decrease in the thickness of the silicon wafer to 20 microns leads to an increase in the capacitance value of the structure on the plateau of C–V-characteristics by 1.7 times and an expansion of the hysteresis loop by several volts. The observed difference in capacitance values on the plateau indicates that Ba_0.8Sr_0.2TiO₃ contacts with Si are not the same in cases with thin and thick substrates. Shifts in C–V-characteristics along the field voltage axis are most likely associated with different embedded charges at the Ba_0.8Sr_0.2TiO₃ — Si interface for cases with thick and thin substrates.